Precision Armament M4 Shoulderless Thread Adaptor 1/2-28 to 5/8-24 Matte Stainless. Muzzle device seats directly against barrel shoulder maintaining full thread joint strength and providing more accurate alignment to bore. Internal and external threads are single point cut in same operation to tight UNEF Class-3 tolerances for perfect concentricity and alignment. The M4 muzzle thread adapter is precision CNC machined from pre-hardened HTSR 400-series stainless steel bar for superior heat and corrosion resistance. Allows the attachment of 5/8-24 muzzle devices to a 1/2-28 1/2-32 or 1/2-36 threaded barrel. NOTE: This thread adapter is intended for more permanent installation of muzzle devices. Specifications for Precision Armament M4 Shoulderless Thread Adapter: Manufacturer: Precision Armament Color: Stainless Finish: Matte Stainless Fabric/Material: HTSR 416 Stainless Steel Bar Weight: 0.2 oz Condition: New Country of Origin: USA Package Contents: Precision Armament M4 Shoulderless Thread Adapter Precision Armament A02410: M4 Shoulderless Thread Adaptor 1/2-28 to 5/8-24 Matte Stainless